package COM.ZYC;

public class Demo4 {
     final double Π = 3.14;

    public double area(int r) {
        return Π * r * r;
    }

    public static void main(String[] args) {
        //数据类型 对象名 = new 类名();
        Demo4 demo4 = new Demo4 ();
        double area = demo4.area(10);
        System.out.println("半径为 10 的圆的面积: " + area);
    }
}



